Heat exchangers



Dec. 3l, 1957 F. LusTwERK ETAL 2,817,960

HEAT EXCHANGERS Filed July 1s, 1954 2 sheets-sheet 1 /N l/ E N TORS F ERD/NAND LUS 7 WERK HAROI. D S. MIC/(L E ATTKS.

Dec. 31, 1957 F.1 us'rwERK l-:rAL 2,817,960

HEAT EXCHANGERS Filed July 15, 1954 2 Sheets-Sheet 2 EVA/ORA roR l 7 GAS suer/0N L l QUID COMP/Pham CONDE/V55@ GAS DISCHARGE wA TER SPRAY /N VEN rolas Fano/NAND Las TWER/r HAROLD s ,wc/L Ey engi/:AEST R Nil/)7mm United States Patent HEAT-',EXCHANGERS Ferdinand Lustwerk, Lincolnf Hroldi S.' l Mic'kley; Belmont, and. Ernest-JP.` Neumann, Lincoln;` Mass., ras, signors, by mesnenassignments;torRheem Manufacturing Company, a corporation of Californian Application-July'135 1954; 'Serial vNot4435028" 3 'Clamsf (Clf. 629-156) This Ainvention relates to' heats: exchangers,` more: parf ticularly to arefrigerant condenser. ofzthe stypezshown Aand described.' inf i ccependingf. application, 'Serial No.' 4275049; led May f3, 195:4;.andlto improvementsrinia refrigeration system embodying said condenser.

Insai;compressionrtype arefrigeration system; a -suitable refrigerant capable of aevaporation.x from ace-liquid L v,to `a gaseousiphase' at flow vtemperature ais circulated `1in; a closed circuit. Whenitrevaporatesrat low pressure in'itlreevapratonfitx. absorbs; heat, .thus `producing :the: desired refrig eration; The evaporated gas f is Acompressed. in-af come presser. and :then-'cooled in; a-.condenser VVto revertlit'toy its liquidfphase yat a substantiallvhi'gher temperaturehthan itsttemperaturexof evaporation: at lowy pressure, after which it returns .to the evaporator,

Our invention. :provides anrirnprovedcondenserandWe haverdiscoveredvthatl the condenser, when used/infA a compression type refrigeration#- circuit, including-means to evaporate and then to compress a refrigerant, increases, efllciency as much as double. This increased'lleiiciency results :ini -partz by V:greatly reducingztheY power-'perf'ton\ of refrigeration required .to compressi `the refrigerant, res ducing power required .to operatenth'e fans,.reducingfthe'` amount of coolant. Water used@ and reducingthepower required to circulate. ithescoolantwater.' Such increased efficiency `is relected in :greatly` reduced' capitalcosts lfor refrigeration yand -air l conditioningunits 'andfthe like'.

The; standard commercial .refrigerating unit,f such fas-is used.- in domestic refrigerators `and airfconditioning-J-sys# tems;V requires a a vmotor rated' ati about `oneshorsepower to-v produce -a ton'rof refrigeration .perrdayg .a tone-.ofcre-rv fxigeration being equivalent to; .that p1' o.dueedr^by-y xthe fmeltinglof-oneton of.-ice. Wefean now-,use a motori'rated; at=one-horsepoWerforfthe-,compressor tof/produce refrigflV eration which is equivalent tofthat. which ,-wassheretoforez produced by. a-.motor rated Tat, ,two..horsepowen In -a refrigeration Asystem,this power.w requirement is proportionate rto the` difference ,between the.. temperatureof evaporation ofthe refrigerant `fromliquidifto gestand. the temperature of 'condensation of.;th'e compressed'. gasV back to liquid; Our invention... increases eflciency ,by reducing the temperature of"condensation lfrom temperatures of the order ofA 125 F.f'andupward in the' usual system L tor v temperatures of the-order-fof 100 or lessr Water is'. the` mostireadilyb-availablefcoolant forfuse wi-th 7Va condenser 1 for cooling refrigerant: When used inl substantialquantities rit ordinarily has'vgoodfcooling prop'-` ertiespbutl such quantitative :useffmaw `amount I:toria xsuba'f stantial iternofffthe cost .offrefrgerationa Many/systeinsak particularly;-fondoxnestic; reftgerationrandz-in'; rf' andi-:rA tioning types;therefore'srelys solelysguponffair -coolingtorf 2,817,960 PatentedDec. .3.1, 1957 condensing the refrigerant; Whilethe'use'of airrfor con.- densing. istfarfless,eicient thanttheordinary use `of water or; vwaterrcombined with air5 theicost. of the water'coolant usually exceedsythe savingnincost offpowerc'required'nfor compression and lno 'ultimatevtotal of savingan .eiiciency is achieved.`

Our. invention contemplates Ather'use fori condensing 1.a refrigerantg.. ofy an fair; stream combinedlwith: Water;rbut the latter in sucht-small quantities :aszto be negligiblein cost:l as comp aredwith i the; saving-inspower.: required for compressing `the'=refrigerantggthereby'"resulting'fin va large over=allsavingsin cost of refrigerationr.

One ofthe substantialimprovementssin:.thefpresent invention lis. in; :the `means byl which: .thcfquantity1 of; cool: ingfwater used'. istreducedby..asystemfzwhich uses .a smaller;` amount 'ofrwater .with :greater -eillcieney andaco1n:-. bined'with means to :re-circulate andfreuse thei,coolant;

For condensing; the coolant water :is :partly evaporated from cooling surfaces rby an .air Vstream andLit is the' excess unevaporatedawater Whichl is. rescirculated and reused:` This .would ordinarilyy result "in antiincreasel of the :con-x centration: of salts .containedrirr the; coolant Watertazwhichare-'deposited in. there-circulation'xsystenrby the ,eVapo-l rated Water,. and such concentrationmwould resultzin' eventual f plugging-.fof 1 the .oricesf and parts:` by'fconcen" trated if. salt. Our 'invention fthereforef: providesimeans '.to drain oif a portion of the re-circulated-.Waterfsor--asnatof maintainlthei. salt concentrationzatz a desirable: working level. Consequently; means are: also `provideditoA replenish thecoolant which is lost byevaporation anddraininga B3n reason -of they advantageous features i ofthe L invention,"` asl will be described',` low pressures and largezoricesfare used: for circulating and .drainingxthezv coo1antwater,l a thereby also substantially leliminatingsthe: likelihoodof :plugging and: ,alsof materially reducing.A cost f not yonly of. the parts of the condenser system but alsoof fthe cost of circulatingt the small amountsiof Water: consumed;

Furtherl advantages .will be-r apparent from the-follow ing description .taken in connection with thezdrawingslzini which:

Figyl isy a side elevation in section. of theA condenser; apparatus of -therinventiom Fig. 2'y is a top plan view with the cover removed;y

Fig.: 3 is a schematicriowdiagramrshowing1thefconL denser. of the .inventionr in combination iwith-v thefotherfl components comprising. the refrigeration system" off in; creased eciency produced by the invention;YAY

Fig. 4 is a front View of the nozzle; and

Fig; 5 is asectionfof y"the'nozzl'e yshownfin 'll'.iig;` 4.

Inthe drawings, Figs. l to'3 show a generallyi'boX-like container-10` having large roundf'openings llflandf 12''in its ends, vthereby forming an airiduct havingt-a-water` tight'v bottom providing av sump 13 containing Water or other coolant lapproximately at the level 'indicated-Sat 14;

In the opening 11 is `attachedlthestructure of--'a@fan-15I arranged with a driving motor. land'fa surrounding duct structure 17"so1as Ato'createy a moving;airistrearnvwhichr enters'an openingf'lS4 in the du'ct 17 andfflowsffrom leftto' right through the' container-10' and outfofsitheopening; 12g/and which air'stream,` due to the'trotationf-of tHe-fana has a vigorous l whirlingr action f.immediately'down-nA streamy ofthefanV 15;

A series of pipes 20, .having manifoldsorfheadersnfzli and-.22 atfth'eir.v ends;.fonn.zconduitmeans irr th'e airistream b'elowff-.thesfanzvlS for cooling; andrcondensingtthe refrigr;

erant which may be conducted into the conduit means by an inlet pipe 23 and away from the conduit means by an outlet pipe 24. Surrounding the conduit pipes 20 and in thermal contact therewith, is an arrangement of cooling tins 30 in close proximity to each other with air spaces between through which the air stream of the fan may ilow, thereby greatly increasing the cooling surface of the conduit pipes 20.

Located approximately axially of the fan 15, and between the fan and the conduit means 20, is a low pressure nozzle 35 having an aperture 36, preferably of the order of 1A inch in diameter or larger,V and of the type illustrated in detail in Figs. 4-5, which delivers a water stream in the form of a wide cone, as illustrated at 38 in Fig. 1, when water is pumped through it from a hose 40 at a pressure of approximately two pounds per square inch. The cooling water is delivered through the hose 40 and the nozzle 35 by a low pressure electrically driven sump pump 45 which is located to draw water 14 from the bottom 13 of the container directly under the nozzle so as to have the shortest possible hose line 40.

Without the aid of the fan 15 the conical stream of water 38 produced by the nozzle 35 plays only on the periphery or surrounding edge areas of the conduit pipes and associated arrangement of tins 30, and a large portion of the central area of the fin arrangement remains dry because no water is projected into the interior of the conical stream of water 38. However, when the fan 15 is in operation, the whirling action of the air stream immediately downstream of the fan agitates the conical stream of water 38 and throws otf droplets of water 39 continuously toward the center of the cone and toward the ns in such a manner that the entire effective surfaces of the fins are continually being wet by droplets of water projected upon them by the combined action of the nozzle and the whirling action of the air stream created by the fan.

There is a point of optimum action of the fan on the water stream relative to which the nozzle should be adjusted and spaced with respect to the fan 15, and also a point where the conduit means may be spaced with respect to the nozzle 35 for optimum wetting etect on the tins by the combined action of the fan and the nozzle, both of which can be determined by adjustment of the parts so that maximum wetting and evaporation effect is produced on the iins 30.

As explained in the said co-pending application, the ns 30 are preferably inclined out of the horizontal from approximately 5 to 15 in order to inhibit by gravitational force the flow of water across their surfaces produced by the air stream. With a corresponding adjustment of air stream velocity and angle of inclination of the fins, the coolant Water is caused to linger on the fin surfaces in an agitated condition, thereby greatly enhancing the evaporation of the coolant and consequently increasing substantially the cooling and condensing eiect on the compressed refrigerant flowing through `the conduits 20.

The critical relative locations of the fan 15, the nozzle 35 and the conduit means 20, as described herein, enable us to use the large aperture low-pressure type nozzle 35 and low-pressure type pump 45 in place of a fine spray type of nozzle which would otherwise be necessary to wet the entire area of the tin, and which requires a high pressure pump to produce such a spray, The advantages are that the low pressure system herein uses less water, the low pressure pump is far cheaper to purchase and operate, and what is more important, the large aperture of the low pressure nozzle is unlikely to clog due to whatever sediment may creep into the system, whereas the multiple line apertures of the high pressure tine spray type nozzle clog more readily and may render the nozzle inoperable after a period of use.

A baille 55 is provided in the form of a fixed highly porous pad to catch the droplets of water driven off the tin surfaces by the air stream and to return them to the sump, while at the same time allowing the flow of the air stream therethrough and out of the opening 12.

Means are provided to drain oit a portion of the water coolant falling from the tins, in order to keep the salt concentration from building up to an undesirable level due to evaporation, in the form of a tray 60 having a drain 62 in the bottom thereof and the edges 64 of which protrude slightly above the water level 14. By this arrangement most of the water flowing off the ns is returned to the sump for re-circulation but a desired proportion falling into the tray 60 is removed.

Means for replenishing the water supply as necessary is provided in the form of a Water inlet 70, automatically controlled by a valve 72 operated by a oat 73 so as to maintain the water level 14 at the desired height. The tray 6) also acts as an overflow in the event the oat valve sticks, thus preventing ooding.

Figure 3 shows the condenser unit 10 connected to receive compressed refrigerant gas through the line 23 and to discharge condensed liquid refrigerant through the line 24 in a closed refrigeration system, including also an evaporator and a compressor 82. The liquid refrigerant is conducted to the evaporator 80 through the line 24 where, upon evaporating it exerts a cooling etfect by absorbing the heat of evaporation, whereupon it passes through a line 84 to the compressor 82 where it is compressed and returned through the line 23 to the condenser 10.

Any of the well known refrigerants, for instance the freon gases, may be used in the system. Whereas, it has ordinarily previously required a motor of one rated horsepower to operate the compressor 82 to produce one ton of refrigeration per day in a refrigeration system of this general type, the power requirement for the compressor 82 has now been substantially reduced as a result of this invention, by reason of the fact that while the evaporation temperature in the evaporator 80 for any given refrigerant remains unchanged, the increased efiiciency of the condenser 10 of the invention substantially reduces the temperature of condensation of :the refrigerant and thereby reduces the power required to cornpress it.

We claim:

1. In a heat exchanger of the character described, conduit means in thermal contact with fins, said fins being inclined from the horizontal about ve to fifteen degrecs, a generally horizontally extending duct providing a passage for a stream of air and in which said conduit means and said tins are positioned with the upper edges of said tins disposed downstream relative to the lower edges, means upstream of said conduit means for supplying liquid to the tins in an amount suticient to continuously maintain substantially the entire surfaces thereof covered with water, a blower positioned upstream of said liquid supplying means to move the air through said duct at a velocity sufcient to substantially completely overcome the gravitational downward How of liquid on the surfaces of said ns.

2. In a heat exchanger of the character described, conduit means in thermal contact with tins, said tins being inclined from the horizontal, a generally horizontally extending duct providing a passage for a stream of air and in which said conduit means and said ns are positioned with the upper edges of said fins disposed downstream relative to the lower edges, means upstream of said conduit means for supplying liquid to the fins in an amount suticient to continuously maintain substantially the entire surfaces thereof covered with liquid, and a blower positioned upstream of said liquid supplying means operative to disperse and distribute the liquid from said liquid supplying means over the entire surfaces of said ns and to move the air through said duct at a velocity suicient to substantially overcome the gravitational ow of liquid on said n surfaces and provide a run-olf of liquid over the upper and lower edges of the fns.

3. The method of cooling a fluid in a conduit comprising passing said uid in the conduit in thermal contact with a n inclined from the horizontal, supplying evaporative liquid upon said fin from adjacent the lower edge thereof and in an amount to substantially completely cover the same, and passing a stream of gas from upstream of the liquid supply so as to disperse and distribute the liquid over the surface of the (in and at a velocity sufficient to substantially completely overcome the free gravitational flow of liquid on the lin and cause a small portion of the liquid to run olf from both the upper and lower edges of the iin.

References Cited in the tile of this patent UNITED STATES PATENTS Anetsberger Apr. 17, Ashley Nov. 3, Bergdoll June 21, Melcher Dec. 29, Young Jan. l4, Wahlin July l, Chapman Mar. 3l, Henney Jan. 3, Hart Jan. l7, Baker May 5, Wile June 8, 

